Use the function item name as the intrinsic's name

Author: oli-obk

compiler/rustc_feature/src/builtin_attrs.rs

@@ -792,7 +792,7 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
         "the `#[rustc_safe_intrinsic]` attribute is used internally to mark intrinsics as safe"
     ),
     rustc_attr!(
-        rustc_intrinsic, Normal, template!(List: "value"), ErrorFollowing,
+        rustc_intrinsic, Normal, template!(Word), ErrorFollowing,
         "the `#[rustc_intrinsic]` attribute is used to declare intrinsics with function bodies",
     ),
 

compiler/rustc_middle/src/ty/util.rs

@@ -1541,15 +1541,9 @@ pub fn is_doc_notable_trait(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
 /// Determines whether an item is an intrinsic by Abi.
 pub fn intrinsic(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Option<Symbol> {
     if matches!(tcx.fn_sig(def_id).skip_binder().abi(), Abi::RustIntrinsic | Abi::PlatformIntrinsic)
+        || tcx.has_attr(def_id, sym::rustc_intrinsic)
     {
         Some(tcx.item_name(def_id.into()))
-    } else if let Some(name) = tcx.get_attr(def_id, sym::rustc_intrinsic) {
-        Some(
-            name.get_normal_item().meta(rustc_span::DUMMY_SP).unwrap().meta_item_list().unwrap()[0]
-                .ident()
-                .unwrap()
-                .name,
-        )
     } else {
         None
     }

library/core/src/intrinsics.rs

@@ -2568,7 +2568,7 @@ extern "rust-intrinsic" {
 #[rustc_nounwind]
 #[unstable(feature = "core_intrinsics", issue = "none")]
 #[rustc_const_stable(feature = "is_val_statically_known", since = "0.0.0")]
-#[cfg_attr(not(bootstrap), rustc_intrinsic(is_val_statically_known))]
+#[cfg_attr(not(bootstrap), rustc_intrinsic)]
 pub const unsafe fn is_val_statically_known<T: Copy>(_arg: T) -> bool {
     false
 }

src/doc/unstable-book/src/language-features/intrinsics.md

@@ -18,8 +18,8 @@ intrinsics without causing any code miscompilations or failures to compile.
 ```rust
 #![feature(core_intrinsics)]
 
-#[rustc_intrinsic(name_of_things)]
-fn foo() -> u32 {
+#[rustc_intrinsic]
+fn some_intrinsic_name() -> u32 {
     42
 }
 ```